UMass Microbiologist Focuses on Iron-Eating Bacteria

Findings have implications on beginning of life on Earth

AMHERST, Mass. -- University of Massachusetts microbiologist Derek Lovley
has made a discovery which opens a window to understanding how life began on
Earth. Lovley has determined that certain kinds of microorganisms, which
live several miles below ground, can use iron to metabolize their food. The
findings are reported in the Sept. 3 issue of the journal Nature, and will be
featured in an upcoming segment of the television show "Discover Magazine,"
on the Discovery Channel.

Lovley, head of the microbiology department, studies unusual forms of
anaerobic microorganisms: in other words, bacteria that transform their food
into energy without using oxygen. "The research helps us to understand life
on Earth a little bit better," Lovley said, "but it also has a practical
side." His previous research has demonstrated that microorganisms that can
grow on iron can be used in treating contaminated groundwater. The
microorganisms use petroleum contaminants, such as benzene, as food, and
literally eat away at contamination. These organisms can also remove toxic
metals such as uranium and chromium from contaminated waters. His most
recent findings focus on "hyperthermophiles": literally, those who love hot
temperatures. Hyperthermophiles are the organisms most closely related to
early forms of life, from which modern bacteria, plants, and animals have
descended, Lovley said.

It was previously believed that some of the first microorganisms used sulfur
to grow. But geologists noted that sulfur did not exist in the proper form
on early Earth. There was, however, abundant iron, so Lovley set about
determining whether iron could serve as an energy source for these early
bacteria. "You can't go back three billion years, but you can study these
hyperthermophiles, which are the modern organisms most closely related to
early life," said Lovley.

Studying seven species of hyperthermophiles, he determined that every single
one could use iron to metabolize its food. This lends weight to the theory
that iron was essential for the growth of early life on Earth, according to
Lovley. One type of hyperthermophile in particular, thermotoga, used iron
in a very central way, and sulfur in a very trivial way, suggesting that
iron was more central to the metabolism of early organisms than sulfur. All
of the hyperthermophiles converted iron oxide to the magnetic mineral,
magnetite, during their growth on iron. This is significant because
geologists have found large accumulations of magnetite on early Earth.
Furthermore, magnetite found deep below the Earth's surface and in a
Martian meteorite has been thought to provide evidence for the possibility
of life existing in these extreme environments.